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Flat-Belt, Gearless Motion Technology Gives Elevators New Lift

Engineers at Otis Elevator Company, Farmington, CT, have specified a unique gearless motion system into the design of the company's Gen2 elevator line. Intended for low-rise and mid-rise buildings (up to 20 floors), the Gen2 represents a major breakthrough in lifting technology. Unlike the familiar heavy steel ropes common in today's elevators, Gen2 uses flat, coated-steel belts driven by a compact gearless drive mounted directly inside the elevator hoistway, instead of requiring a separate machine room above the shaft.

The system is built around a high-performance DC brushless servomotor manufactured by Kollmorgen Corporation in Radford, VA. The motor has no commutators or brushes to wear down, so it provides long maintenance-free operation, lower operating costs and extremely smooth operation at high motor speeds to improve rider comfort. In addition, the flat-belt design of Gen2 uses a small-diameter traction sheave, which can be directly driven by the high torque of a small permanent magnet motor. This, in turn, allows for a significant reduction in machine size.

"The traction sheave is now an integral part of the motor shaft," explains Olivier Robert, senior vice president of operations at Otis, "not a separate component as in traditional elevators. The expertise that Kollmorgen brings as co-developer of the Gen2 machine is something we didn't have, and it would have taken us too long to develop in-house."

In its search for a Gen2 partner, Otis designers looked for a supplier with permanent magnet motor technology -- a technology already proven in the marketplace. Speed to market was also important, according to Willy Verbrugghe, president of Kollmorgen's Industrial and Commercial Group. In December 1998, Otis wanted a custom servomotor design with such advanced specifications that it could have easily taken two years or more to develop. "Instead, we built a near-perfect prototype in six months and were able to deliver production units in less than 13 months," says Verbrugghe.

According to Otis, the Gen2 will be launched in European markets this spring, in Asia later this year, and it will be available worldwide in 2001. --KC

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